Composition for earth compacting

ABSTRACT

A method for making a dirt road base, which method comprises loosening the ground to a depth of at least about two inches, mixing the loosened earth with an aqueous dispersion of asphalt containing dispersed calcium hydroxide, to provide it with moisture and asphalt contents that give it the desired strength after compacting, and then rolling the mixed product to form the desired base.

United States Patent [1 1 Azar et al.

[ COMPOSITION FOR EARTH COMPACTING [75] Inventors: David Azar; Keith P.Lanneau, both of Baton Rouge, La.

[73] Assignee: Roadways International Corporation, Baton Rouge, La.

22 Filed: Nov. 28, 1973 21 Appl. No.: 419,867

Related US. Application Data [62] Division of Ser. No. 199,758, Nov. 17,1971, Pat. No.

[52] US. Cl 260/285 AS; 106/277; 106/281; 260/174 SG [51] Int. Cl. C08L95/00 [58] Field of Search 260/l7.4 56, 28.5 AS; 106/277, 281

[56] References Cited UNlTED STATES PATENTS 2,454,506 3/1974 Fischer260/765 [451 Oct. 14, 1975 2,789,917 4/1957 Hardman et a1. 106/2773,085,889 4/1963 Swifi 106/277 3,206,319 9/1965 Minnick et a]... 106/2773,520,709 7/1970 Mogg et al. 106/277 3,577,250 5/1971 Rostler 106/277Primary Examiner-Melvyn I. Marquis Attorney, Agent, or Firm-Connolly &Hutz ABSTRACT 6 Claims, No Drawings COMPOSITION FOR EARTH COMPACTINGThis application is a division of application Ser. No. 199,758 filedNov. 17, 1971, US. Pat. No. 3,817,643 granted June 18, 1974.

The present invention relates to bases for roadways that carry traffic,and to compositions for forming such bases.

Among the objects of the present invention is the provision of a novelmethod for forming road bases, as well as novel compositions for use insuch formation.

The foregoing as well as additional objects of the present inventionwill be more fully presented by the following description of several ofits exemplifications.

According to the present invention a good quality roadway base isinexpensively made by loosening the ground to a depth of two to sixinches, mixing the 100s ened earth with an aqueous asphalt emulsioncontaining dispersed calcium hydroxide in an amount about 5 to by weightof the asphalt, and then compacting the mixed material by rolling toform the desired roadway base. The proportion of the emulsion mixed withthe earth can be varied so as to provide an asphalt concentration thatprovides the desired strength for the completed base, and the dilutionof the emulsion can be varied to provide the compacted earth mixturewith the optimum moisture content that develops the desired strength.

It is a feature of the present invention that not only does the asphaltcontribute substantial strengthening, but the calcium hydroxide assistsin getting the asphalt thoroughly distributed in the loosened earth.This assistance is particularly important where the earth has asignificant clay content. Simple asphalt emulsions will not penetrate orwill not adequately penetrate into clay and will not properly strengthenclayey earth, but the presence of the calcium hydroxide in the asphaltemulsion pursuant to the present invention greatly improves thepenetration obtained when the emulsions are mixed with the loosenedearth.

Even in sandy type soils the calcium hydroxide helps inasmuch as calciumhydroxide particles are deposited among the sand grains and may increasethe strength of the non-cohesive sand.

The asphalt emulsions containing calcium hydroxide give even betterresults when they also contain a little tack-providing rubber. Onlyabout 1 to 3% of such rubber based on the weight of the asphalt issufficient for this purpose.

Where the emulsions are to be stored it is also helpful to add to themabout A to 2% sugar (sucrose). This reduces the tendency for the calciumhydroxide particles to pack upon standing. The calcium hydroxide ispresent in an amount greater than that which dissolves in the aqueousphase of the emulsion so that most of the calcium hydroxide is in theform of suspended particles, and these particles settle to the bottom ofthe container on standing. ln the presence of the sugar the settledparticles are readily re-dispersed upon mild agitation; without thesugar the settled particles pack and may need forceful disturbancebefore they are redispersed.

The following is a preferred example of an emulsion formulationaccording to the present invention:

230 gallons -Continued pentadecaethoxy ethanol (35% by The ingredientsare mixed in the order listed, and the formulation is then ready forimmediate use or for storage and/or shipment. The second ingredient is astabilizer and where the formulation is to be used within about 48 hoursand is not shipped any significant distance or subjected to freezing,the stabilizer content can be reduced to about half that shown.

The asphalt of the foregoing emulsion has a moderate penetration (40 toat 77F for 5 seconds with a gram weight) and a low softening temperature(about 118F). Higher softening temperatures are not desirable, but canbe used effectively in the warmer climates. Asphalts with softeningtemperatures below about 90F 100F are generally sufficiently sticky tobe used with very little or no rubber.

Asphalts of varying hardness can be used in the formulations of thepresent invention, with penetrations as great as 200 and as small as 30.

The formulations of the present invention can be anionic, non'ionic orcationic dispersions. The asphalt emulsion and rubber latex ingredientsof these formulations should not be of such character that they reacttogether to cause flocculation. Thus when the asphalt emulsion isanionic the latex can be anionic or nonionic; when the asphalt emulsionis cationic the latex can be cationic or non-ionic; and when the asphaltemulsion is non-ionic the latex can be non-ionic, anionic or cationic.

While the p-octyl phenoxy polyethoxy phenols have been foundparticularly effective in stabilizing the formulations of the presentinvention, especially when there are at least six ethylene oxide groupsin the polyethoxy chain connecting the ethanol group with the benzenering, other stabilizers such as the anionic, nonionic, cationic andamphoteric'stabilizers referred to in US. Patent No. 3,418,249 grantedDec. 24, 1968, can also be used. Larger quantities of these otherstabilizers might be desirable however.

It is preferred that the rubber, where used, have a fairly low softeningtemperature so as to provide a highly desirable tack at below-groundlevels where the temperature can be as low as 50F or lower. Othertack-providing rubbers of latices such as EPR (ethylene-propylenecopolymer rubber) can be used in place of the SBR rubber, and even theless weather-resistant types of rubber such as natural rubber can beused.

For best results the following procedure should be used in building theroadway base according to the present invention;

1. The first step is to break or scarify the road to the depth for whichstabilization is desired (usually 2-6 inches). This may be accomplishedon either dirt or mixed dirt-gravel roads by using a scarifierattachment on a motor grader. In proceeding with this first step it isassumed that the road or street is already properly drained and at theapproximate grade desired.

2. It is desirable to break up and pulverize the soil as well aspossible, mixing the soil well with any aggregate present. Ideally, thisshould be continued until approximately 80% of the soil, excludingaggregate, will pass a No. 4 sieve.

3. When soil pulverizing and shaping is completed it is preferable towindrow the soil to the side of the road. Then a pass is made with aspray truck that applies the formulation of the present inventionappropriately diluted with additional water. Only about half of thetotal amount of the formulation is applied in this pass. The soil isthen bladed over with a motor grader to get good mixing of the appliedformulation with the soil. At least one more pass of the spray truck ismade to apply the balance of the formulation, after which the soil isagain mixed with the motor grader. The mixing is preferably effectedimmediately after the application of the formulation, as by having themotor grader closely follow the spray truck. A typical application to asoil that is about 25% clay is about 1 gallon of the abovedescribedformulation per square yard of 4 inch depth roadbed, the formulationbeing first diluted 1:5 with additional water. However the dilution canrange from about 1:1 to about 1:10 and the total amount of formulationcan vary from about 2/10 to about 2 gallons per square yard 4 inchesdeep. The exact dilution and amount of application is best determined bytesting samples of the loosened soil, each with a different amount ofadded formulation. Such samples can be compacted into cylinders, curedby baking at 150F for 3 hours, followed by 2 hours standing at roomtemperature, after which they are placed in contact with water for fourhours. The resulting cylinders are then subjected to greater and greatercompacting pressures to determine how much they will withstand. Thisfinal compaction can be effected in cylindrical frames having sideopenings through which the soil will be forced when the compactingpressure exceeds that which the soil will withstand. The minimum amountof formulation required to attain specification pressure is thenselected.

The amount of dilution is then adjusted so that the freshly mixed soilis brought to the optimum moisture content for compaction. This contentcan also be tested by a compacting operation without preliminary curing.

4. The final mixed soil is now compacted as by means of 5 to passes witheither a heavy steel or rubbertired roller. Ideally compaction shouldtake place when the soil is either at or slightly below optimum moisturelevel. lf the soil has inadvertently been over-wetted during thestabilization steps, the road should be allowed to dry until the excessmoisture is dissipated.

The compactor will leave the road in a hard smooth condition practicallyready to receive a blacktop pavement or even a concrete pavement. Beforea blacktop covering is applied the roadbed can be given a further lightcoating of asphalt from a solution in a suitable solvent such asnaphtha. About 0.1 to 0.2 gallon of such a solution of asphalt persquare yard provides a seal coat and a temporary riding surface thatwill withstand light traffic such as light airplanes, for as long as ayear. This will also act as a primer to better receive the blacktop.

Where the final roadway is only subjected to light loads, as for examplewhen used as a landing strip for light airplanes, the roadbed with theprimer coating is all that is needed. Regardless of how used, however,the roadbed of the present invention is very inexpensive to prepare anddoes a creditable job.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed:

1. An article of commerce which is essentially an aqueous emulsion ofearth-penetrating asphalt containing dispersed particles of calciumhydroxide in an amount greater that 5% based on the weight of theasphalt and so large that most of these particles do not dissolve butare suspended in the emulsion, the asphalt concentration being at leastabout 5% by weight of the composition.

2. The combination of claim 1 in which the asphalt concentration is atleast about 40% by weight and the composition contains an anti-packingagent in an amount that keeps the calcium hydroxide particles frompacking.

3. The combination of claim 1 in which the composition also contains adispersed tack-providing amount of rubber.

4. A concentrate for mixing with earth to prepare it for compacting, theconcentrate being essentially a concentrated aqueous emulsion ofearth-penetrating asphalt containing a dispersed tack-providing amountof rubber, and also containing dispersed particles of calcium hydroxidein an amount greater than 5% based on the weight of the asphalt and solarge that most of these particles do not dissolve but are suspended inthe emulsion.

5. The combination of.claim 4 in which the calcium hydroxide content ofthe concentrate is no greater than 20% based on the weight of theasphalt, the rubber content of the concentrate is from about 1 to about3% based on the weight of the asphalt, and the concentrate also containsabout to 2% sugar.

6. The combination of claim 4 in which the emulsion also contains ananti-packing agent in an amount that keeps the calcium hydroxideparticles from packing.

1. AN ARTICLE OF COMMERCE WHICH IS ESSENTIALLY AN AQUEOUS EMULSION OFEARTH-PENETRATING ASPHALT CONTAINING DISPERSED PARTICLES OF CALCIUMHYDROXIDE IN AN AMOUNT GREATER THAT 5% BASED ON THE WEIGHT OF THEASPHALT AND SO LARGE THAT MOST OF THESE PARTICLES DO NOT DISSOLVE BUTARE SUSPENDED IN THE EMULSION, THE ASPHALT CONCENTRATION BEING AT LEASTABOUT 5% BY WEIGHT OF THE COMPOSITION.
 2. The combination of claim 1 inwhich the asphalt concentration is at least about 40% by weight and thecomposition contains an anti-packing agent in an amount that keeps thecalcium hydroxide particles from packing.
 3. The combination of claim 1in which the composition also contains a dispersed tack-providing amountof rubber.
 4. A concentrate for mixing with earth to prepare it forcompacting, the concentrate being essentially a concentrated aqueousemulsion of earth-penetrating asphalt containing a dispersedtack-providing amount of rubber, and also containing dispersed particlesof calcium hydroxide in an amount greater than 5% based on the weight ofthe asphalt and so large that most of these particles do not dissolvebut are suspended in the emulsion.
 5. The combination of claim 4 inwhich the calcium hydroxide content of the concentrate is no greaterthan 20% based on the weight of the asphalt, the rubber content of theconcentrate is from about 1 to about 3% based on the weight of theasphalt, and the concentrate also contains about 1/2 to 2% sugar.
 6. Thecombination of claim 4 in which the emulsion also contains ananti-packing agent in an amount that keeps the calcium hydroxideparticles from packing.